What is a Kernel in OS? What are the types of Kernel?

All operating systems, whether Windows, Mac, Linux or Android, have a main program called Core who acts as the "boss" of the entire system. It's the heart of the bones! The kernel is nothing but a computer program that controls everything else. Everything that happens on the computer goes through it. In this post, we will discuss what is a kernel in an operating system and different types of kernels.

What is a kernel in an operating system?

Now that we know this is an essential program in the operating system, you should also know that it is also the first program that loads after the boot loader. It then makes the whole dialogue between hardware and software or applications. So, if you run a program, the user interface sends a query to the kernel. The kernel then sends a request to the CPU, to the memory to allocate processing power, memory, etc., so that the application can run smoothly in the front-end interface.

You can imagine Kernel as a translator. It converts software input / output queries into a set of instructions for the CPU and GPU. In simple terms, it's a layer between software and hardware that makes everything possible. The kernel manages the following:

1. CPU / GPU
2. Memory
3. Input / output devices or IO
4. Resource management
5. Memory management
6. Device Management
7. System calls.

User processes can access kernel space only through system calls. If a program tries to access it directly, it will cause an error.

Kernel security and protection

The core also protects the hardware. If there is no protection, any program will be able to perform any task on the computer, including the crash of your computer, data corruption etc.

In modern computers, security is implemented at the hardware level. For example, Windows will not load drivers that do not come from a trusted source and that are certified with the help of a signature. Secure Boot and Trusted Boot are classic examples.

Secure boot: This is a security standard developed by members of the PC industry. It helps protect your system against malware by preventing unauthorized application from running during the system startup process. This feature helps ensure that your PC only boots up using software that is approved by the PC manufacturer. Thus, each time your computer starts, the firmware checks the signature of each startup software, including the firmware drivers (optional ROMs) and the operating system. If the signatures are verified, the PC starts and the firmware gives control to the operating system.

Approved startup: It uses the Virtual Trusted Platform Module (VTPM) to check the digital signature of the Windows 10 kernel before loading it. In turn, it confirms all other components of the Windows startup process, including boot drivers, startup files, and ELAM. If a file has been corrupted or modified, the boot loader detects it and refuses to load it by recognizing it as the damaged component. In short, it provides a chain of trust for all items at startup.

What are the core types

The kernel can also communicate with the hardware on a secure line. Thus, companies can develop a kernel capable of communicating with their hardware via a set of buttons. Take the example of the washing machine. Depending on the buttons you move and the time you set, a basic kernel level should be sufficient. That said, the nuclei themselves become complicated over time, resulting in types of nuclei.

1. Monolithic core: Here, the operating system and the kernel both run in the same memory space and are suitable when security is not a major concern. This results in faster access, but if there is a bug in the device driver, the entire system crashes.
2. Microkernel: This is a lite version of the monolithic kernel where the kernel itself can do most of the work without the need for additional graphical interface. They should be used where safety and the broken down system do not occur or will not occur.
3. Hybrid core: This core is what we see most. Windows, Apple MacOS. They are a mixture of monolithic and microkernel nuclei. It removes the drivers but keeps the system services in the kernel – in the same way that the drivers are loaded when Windows starts the boot process.
4. Nano Core: If you need a kernel, but the majority of its functions is configured externally, this comes into play.
5. Exo kernel: This core provides only process protection and resource management. However, it is mainly used when you test an internal project and upgrade to a better type of kernel.

There is a lot more to a kernel than we talked about. As you deepen your search, the definition of the kernel becomes broader and deeper.

We hope the post was easy to understand and will help you get through the basics.